tilt/trim drive questions

brian2001ss

brian2001ss

New Member
Jun 18, 2007
243
Lake Lure, NC
Boat Info
boatless
Engines
boatless
I did some searching, but how does the angle of the drive effect the performance of the boat? From my experience, I have a pretty good idea how it does, but I wanted to see what your comments would be. I know when boating not to have the drive up all the way because its bad on the unit, but does having the drive all the way down effect it in the same way? I guess my questions in general would be why and where do you trim the drive for the different conditions you have/face like skiing, towables, heavy wake, cruising at a higher speeds, wake boarding, and so on?
 
When starting or turning drive all the way down which forces the nose down a little. When on plane I hit the trim up button usually 3 times (on the trim gauge it will be not quite to 1/4 up) and you will notice the RPM move up a little and the boat get faster. When going into a turn again I will usually trim down and repeat. I never have the trim up more than 3/4 up (1/4 Down) and that is usually just when starting the boat at the ramp. Now here is the real world if the water is rough (saturday late afternoon on the lake) I will leave the drive all the way down so that the ride is smoother also I am not really looking for top speed. I also do this sometimes because it seems to burn more fuel and I like to run the tanks as close to empty as possible prior to trailering home. With skiers or tubers or wakeboarders I personally leave the trim down as it creates a bigger wake and one less thing I have to worry about. Not sure if that is the right answer but that is what I do....I may learn something on this one that I am doing wrong. :thumbsup:
 
First Born said:
When starting or turning drive all the way down which forces the nose down a little. When on plane I hit the trim up button usually 3 times (on the trim gauge it will be not quite to 1/4 up) and you will notice the RPM move up a little and the boat get faster. When going into a turn again I will usually trim down and repeat. I never have the trim up more than 3/4 up (1/4 Down) and that is usually just when starting the boat at the ramp. Now here is the real world if the water is rough (saturday late afternoon on the lake) I will leave the drive all the way down so that the ride is smoother also I am not really looking for top speed. I also do this sometimes because it seems to burn more fuel and I like to run the tanks as close to empty as possible prior to trailering home. With skiers or tubers or wakeboarders I personally leave the trim down as it creates a bigger wake and one less thing I have to worry about. Not sure if that is the right answer but that is what I do....I may learn something on this one that I am doing wrong. :thumbsup:
Click to expand...

Thanks Wes. Makes alot of sense.
 
When kneeboarding or tubing, I tend to keep the trim close to all the way down to get up on plane. I may move it up a little as we get on plane but no more than 1/4 up. If we are cruising and the lake is calm, I will put it down to get on plane and then slowly trim up to increase speed. I don't normally go past the half way point. This seems to be here I get a good cruising speed on a calm lake. If the local lake gets a little choppy I tend to keep the trim down more like Wes said to make the ride smoother. When on Lake Erie where the chop is more of rolling waves, I will trim up a little more to keep the bow up out of the water and take less chance of burying the nose of the boat in a wave. If it is that bad I also run with the bow cover on.
 
Since we are talking about boats with out trim tabs, Wesley pretty much hit the nail on the head. Trim down for hole shot, trim up all other times except for maybe ride/water issues. As to adjusting the trim after come up on plan. You make small adjustments trimming up to find the sweet spot. Listen to the motor/feel the boat and watch the RPMS . Motor just sounds right and all slight vibrations will be removed from the boat ride(Not sure how to describe it). The RPMS will go up with out adding any more power. You may even have to reduce power if you are trying for best cruise/fuel range. Most of the time this is some where around 1/2 trim. Once I get mine set don't touch it again.

Now if we are talking about pulling skiers/tubers(Kids, small adults). I just bump the trim button up a couple times and leave it alone. Now if I'm fully loaded(lots of people/weight on the boat) and pulling a large skier up then I just trim all the way down.


When going into a turn again I will usually trim down and repeat.
Click to expand...
Wesley why are you adjusting while turning? Are you coming off plane/reducing speed that much?
 
If I am going to make a 180 turn it seems to stick better with the trim down, when in the trim up position (1/4 up) it seems to slide across the water and I feel like I need to make a wider turn. When I put the trim all the way down it seems to grab and I could turn as hard as I want and the boat feels completely in control. Part of it goes back to that is what the captain that went out with me when I bought the boat explained to me and it is just natural now. Not saying I always do but I normally do trim down.

Chuck why are you questioning me :huh:
 
Trimming up lifts the forward portion of the hull out of the water and reduces drag. Trimming down is the opposite, it lowers the hull into the water and increases drag. Speed and efficiency increases when trimming up.
 
First Born said:
If I am going to make a 180 turn it seems to stick better with the trim down, when in the trim up position (1/4 up) it seems to slide across the water and I feel like I need to make a wider turn. When I put the trim all the way down it seems to grab and I could turn as hard as I want and the boat feels completely in control. Part of it goes back to that is what the captain that went out with me when I bought the boat explained to me and it is just natural now. Not saying I always do but I normally do trim down.

Chuck why are you questioning me :huh:
Click to expand...


I guess I was not thinking about a 180 degree turn, I was thinking more of a 90 degree turn and I've never felt like I needed to trim down for a 90 degree turn. Yes on 180 degree turn I can see where you would get more of a bite on the water with the bow down.
 
Well this past Sunday I tried tubing, wake boarding, and skiing with the drive all the way down, and it made a huge difference. We had 8 people and started out with a full tank of gas. Only had trouble pulling one wake boarder out of the water. Its amazing how slow your boat can feel when your pushing a ton of water in front of a wake board.

Thanks for the tips guys.
 
I agree with all of the above, except when really running it(I like to go fast sometimes), I have the trim a hair above 3/4 up. That is where the rush of the water is the quietest and I max out the top speed. This is what I was told on my test drive with the SR dealership owner on my last drive before taking delivery and repeated by the captain on my familiarity cruise upon taking delivery. Neither one said to trim to "X", they just told me to trim up until I could hear the water noise quiet down and the rumble of the motor go away. It just happens that it is right above 3/4. This is the first I have heard that certain attainable geometry angles can tear things up. Please let me know if I shouldn't be trimming this high. :huh: Thanks.
 
3/4 UP on trim? Or 3/4 DOWN on trim (1/4 up)? If you're trimming 3/4 UP, that is much too great of an angle for U-joint longevity.

Doug
 
Brian

Trimming the drive serves one purpose and that is to get the boat out of the water thereby reducing the "wetted" (or friction) surface which gives you the best speed and burns the least amount of fuel to boot.

On my 240SD I could tell when it was trimmed perfectly just by watching the speedometer. You could actually see the boat pickup a bit of speed when trimmed properly or loose speed when not trimmed properly. In rough water conditions you may want to trim the drive down so the bow of the boat cuts thru the waves instead of slamming over them with a bow up attitude. When first starting out the drive needs to be trimmed down to give you the fastest time-to-plane.

There really isn't any more to it than that unless you have trim tabs........but thats another story.

Dave
 
matthewmiller01 said:
I agree with all of the above, except when really running it(I like to go fast sometimes), I have the trim a hair above 3/4 up. That is where the rush of the water is the quietest and I max out the top speed. This is what I was told on my test drive with the SR dealership owner on my last drive before taking delivery and repeated by the captain on my familiarity cruise upon taking delivery. Neither one said to trim to "X", they just told me to trim up until I could hear the water noise quiet down and the rumble of the motor go away. It just happens that it is right above 3/4. This is the first I have heard that certain attainable geometry angles can tear things up. Please let me know if I shouldn't be trimming this high. :huh: Thanks.
Click to expand...

As long as you are staying in the trim limit range you are fine, I usually trim about 3/4 up with the trim button, the trim limit switch will stop you before you get into a danger range. :grin:
 
That's interesting. My trim (without using the trailer trim range) will only go up to just past 50%, which is the fastest trim level speed wise.
 
douglee25 said:
3/4 UP on trim? Or 3/4 DOWN on trim (1/4 up)? If you're trimming 3/4 UP, that is much too great of an angle for U-joint longevity.

Doug
Click to expand...

Yes, 3/4 UP (1/4 from the stop before going into the trailer range).

midway said:
As long as you are staying in the trim limit range you are fine, I usually trim about 3/4 up with the trim button, the trim limit switch will stop you before you get into a danger range. :grin:
Click to expand...

This is what I figured, but after reading this thread, I was concerned.

New Bob said:
That's interesting. My trim (without using the trailer trim range) will only go up to just past 50%, which is the fastest trim level speed wise.
Click to expand...

Mine will go all the way up to the stop (and beyond if I go to the trailer range).
 
As long as your within the normal operating trim range I don't see what the worry is. I just ran 4hrs steady at about 28mph. The drive was trimmed to what appeared/felt most efficient at that speed. I think the actual operating trim range would be restricted more by the manufacturer if there were mechanical problems generated by this kind of use.
 
At WOT I have the trim at the halfway mark...seems to give the fastest, smoothest ride at optimal rpm's of just under 5k.

When wakeboarding, we trim up just a hair depending on load in the boat, and speed at which the rider wants. I have to say Im impressed with the wake for a runabout.
 
1/4, 1/2 and 3/4 are also subject to the accuracy of the gauge. I'm guessing you are making these judgements based on the dash gauge? Those aren't exactly the most accurate. Instead they just give you a general feel for where it's at. So 3/4 on one might translate to 1/2 or 1/4 on the other. I have two and they are both out of whack! I'm no expert in this area by any means! I think if you trim it out and the speed picks up, the drive is still in the water then you are fine. If you trim too far up, you will lose speed and see a nasty roostertail! :grin:
 
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